curl_multi_timeout(3) Library Functions Manual curl_multi_timeout(3)
NAME
curl_multi_timeout - how long to wait for action before proceeding
SYNOPSIS
#include <curl/curl.h>
CURLMcode curl_multi_timeout(CURLM *multi_handle, long *timeout);
DESCRIPTION
An application using the libcurl multi interface should call
curl_multi_timeout(3) to figure out how long it should wait for socket
actions - at most - before proceeding.
Proceeding means either doing the socket-style timeout action: call the
curl_multi_socket_action(3) function with the sockfd argument set to
CURL_SOCKET_TIMEOUT, or call curl_multi_perform(3) if you are using the
simpler and older multi interface approach.
The timeout value returned in the long timeout_ms points to, is in
number of milliseconds at this moment. If 0, it means you should
proceed immediately without waiting for anything. If it returns -1,
there is no timeout at all set.
An application that uses the multi_socket API should not use this
function. It should instead use the CURLMOPT_TIMERFUNCTION(3) option
for proper and desired behavior.
Note: if libcurl returns a -1 timeout here, it means that libcurl
currently has no stored timeout value. You must not wait too long (more
than a few seconds perhaps) before you call curl_multi_perform(3)
again.
PROTOCOLS
This functionality affects all supported protocols
EXAMPLE
int main(void)
{
struct timeval timeout;
long timeo;
fd_set fdread;
fd_set fdwrite;
fd_set fdexcep;
int maxfd = 2;
CURLM *multi = curl_multi_init();
curl_multi_timeout(multi, &timeo);
if(timeo < 0)
/* no set timeout, use a default */
timeo = 980;
timeout.tv_sec = timeo / 1000;
timeout.tv_usec = (timeo % 1000) * 1000;
/* wait for activities no longer than the set timeout */
select(maxfd + 1, &fdread, &fdwrite, &fdexcep, &timeout);
}
TYPICAL USAGE
Call curl_multi_timeout(3), then wait for action on the sockets. Figure
out which sockets to wait for by calling curl_multi_fdset(3).
When there is activity or timeout, call curl_multi_perform(3) and then
loop - until all transfers are complete.
AVAILABILITY
Added in curl 7.15.4
RETURN VALUE
This function returns a CURLMcode indicating success or error.
CURLM_OK (0) means everything was OK, non-zero means an error occurred,
see libcurl-errors(3).
SEE ALSO
curl_multi_fdset(3), curl_multi_info_read(3), curl_multi_setopt(3),
curl_multi_socket(3)
libcurl 2026-06-09 curl_multi_timeout(3)
curl 8.20.0 - Generated Tue Jun 9 12:57:16 CDT 2026